It's a cyber secret some of them like to keep from their tech-challenged parents. I think of myself as a savvy dad, but I was shocked by some of what I found on the site. Friday night on Dateline we'll show you what you need to know about MySpace and other social networking sites to keep your kids safe.

MySpace is sort of a cyber diary, yearbook and social club. It's free, easy to join, and easy to message other members. You're supposed to be at least 14 to sign up but we found younger kids using it. Kids design their own MySpace page and most chat back and forth about school, sports, gossip etc.

What many of them don't realize is that millions of people have access to the pictures and personal information they post. Police say in some cases sexual predators are using that information to find kids. One Internet safety expert said for a pedophile, it can be "one stop shopping by catalogue."

Read Chris' answers to questions MSNBC's Dan Abrams had for him about the latest report. Abrams asked about whether or not charges were filed against men in previous reports; and Chris Hansen admits that confronting these potential predators... hasn't really gotten any easier.

It was almost two years ago when the first in a series of breakthrough investigations exposed a national epidemic: grown men trolling the Internet, many looking for sex with minors.

In two different investigations, in two different states, dozens of men showed up at our undercover houses after chatting about sex online and then making a date with a minor. Both of our investigations were watched by millions of people. It was the talk of radio and cable television shows for weeks.

So have sexual predators learned any lesson at all?

Apparently not. Just this week, Dateline was back in action for a third investigation, this time in Southern California. As you’ll see, some men are simply not getting the message.

Daniel Pulido was hoping to meet a 13-year-old girl home alone. He sent her pictures over the Internet of his genitals, and then asked if she’d give him oral sex. He was in for a big surprise when I walked in. Like so many others, he says he didn’t go to the house for sex, and was there to teach the girl a lesson about the dangers of talking to strangers online.

Chris Hansen (hidden camera footage): So you posed naked on your webcam so a 13-year-old girl could see it because you wanted to teach her a lesson.

Daniel Pulido: Well, you could say that.

Hansen: So is this a like a tough love thing?

Hansen: did you bring condoms with you?

Pulido: Actually I did.

Hansen: And what part of the lesson would that be?

Pulido: I wasn’t going to use. I was going to give them to her.

Daniel Pulido may really be the one who needs to learn a lesson. You won’t believe what he admits to me.

Hansen: Do you ever watch Dateline NBC?

Pulido: Yes.

Hansen: Have you ever seen our stories on computer predators?

Pulido: Yes.

Hansen: This is one of them.

Unlike our previous hidden camera operations, where after leaving the house some men were able to make a run for it, this time things will be different.

For our new investigation, Perverted Justice, the watchdog group that regularly catches online predators, set up a plan with the Riverside County Sheriff’s Department. Frag, a Perverted Justice volunteer who is inside the house alerts detectives when a potential predator is on the way. Once the man leaves the house—he can run, but he can’t hide.

Daniel Pulido is just one in another parade of potential predators. We thought we’d heard it all, but nothing could prepare us for the kinds of thing we found during our latest investigation.

Hansen: If he would have consented to having sex, what would have happened?

“Chuck” another potential predator: I’d be very hesitant at first if he would have continued. Then, possibly we would have had had it.

Hansen: Possibly, you would have had sex with a 13 year old boy?

Dozens of men show up, some of who’ve already been convicted of sex crimes with minors.

Hansen: so you’re on probation for having sex with a boy how old?

“Robert,” another potential predator: 15.

Hansen: And now you’re here to have sex with a 13-year-old?

While our first two investigations saw almost 20 men show up each time, as you’ll soon see, those numbers were dwarfed by what we found in our latest investigation in Southern California.

You can see our full investigation three weeks from tonight: "To Catch a Predator III" airs February 3rd, 9 p.m., 8 Central on Dateline.

The story got a tremendous response from parents. Now, there’s some new information about some of the men caught by our cameras.

On Friday, Dec. 16, Dateline brings you the next step in the investigation. 8 p.m./ 7 C.

What happened to those men? (Chris Hansen)

During our investigation into potential online predators, we saw a parade of men show up at what seemed to be a typical suburban Virginia house.

In 3 days, 19 men arrived in a house, men who thought they had arranged a date online with a young teen.

They met me instead, and immediately some of these men headed for the door. But others stayed, apparently believing I was the child’s father or with law enforcement. None of them knew our hidden cameras were recording their every move.

One man, an army sergeant, not only tried to entice our decoy into having sex, he even wanted to include a dog.

And perhaps more shocking than the number of men is who they are: One was a 54-year-old special education teacher, another a 50-year-old is an emergency room doctor. When I confronted the doctor, he said he had no intention of having sex with a 14-year-old boy and that he only came to the house because he felt badly for the teen who was left home alone.

The doctor, like most of the men who showed up at our house, maintained he was not doing anything wrong.

We even had a man strip naked in our garage after our decoy asked him to. That same 43-year-old showed up with a 12-pack of beer, thinking he was meeting a 14-year-old boy. He got his chance to tell his story to police last week when he was taken in for questioning. Detectives confiscated computers and other items from his home. He has not been charged with a crime.

We told you in our first report that the rabbi resigned and the teacher was fired. On the day our report aired, the doctor’s hospital privileges were suspended and he was also fired.

Meetings. Hours of editing tape and reviewing transcripts. Still more meetings. The Dateline NBC investigations featured
here have something in common: they are the products of a series of steps and a set of principles that help us decide when and how to use this powerful but controversial technique. Today, as viewers demand more transparency from journalists, it’s especially important that we explain why we think hidden camera is an important part of our work.

Hidden cameras let us get close to people who, if they knew our plans, might well change their behavior, and that helps explain why you find hidden camera work in some of the most important investigations Dateline NBC has broadcast. But because the use of hidden camera — and our failure to identify ourselves as journalists up front — is so different from our usual methods of gathering information, we take care to limit its use to situations where we have an important story to tell, and strongly suspect that introducing ourselves would make that story evaporate. Would vendors serve an identifiable NBC News crew more beers than their rules allowed? Would potential Internet predators behave the same way if they knew we were watching? In each of these cases, we concluded that we needed to get to the story without introducing ourselves first.

Other factors are at work before our journalists begin. We meet to discuss journalism and editorial policy issues the story might raise. Our lawyers check to be sure our investigation is legal— relevant privacy and taping laws vary from state to state. And after the material is gathered, but before you see it, we take a close look at what we have, aiming always to give subjects a full and fair chance to respond to what we captured. We also think hard about what to include, making sure you get to hear what the subjects of our investigations have to say.

That said, each of these stories posed different challenges and prompted serious discussions. The Internet predator spot, for example, meant we spent a lot of time reading complete transcripts of the online chats between Perverted-Justice volunteers, posing as sexually available teens, and the men who chose to talk to them. We struggled to share this material with you without running afoul of good taste because the chats drove home just how unwelcome these men would be in the life of your child. If you watch the hour, pay attention to our explanations of how and why we came to report this extraordinary story. I hope we did a good enough job of explaining our decisions, and I hope you’ll share your responses with us.

Late last August three hidden camera engineers, 2 regular cameramen, a soundman, 2 volunteers from a vigilante group that exposes computer predators, a producer, an associate producer, a security provider and I moved into a big home in an affluent suburb of Washington, DC. The mission: to explore the sometimes dark world of Internet chat rooms and to expose predators who seek to seduce children.

We all knew going in that the scope of the problem is immense. At any given time 50,000 predators are on the Internet prowling for children and the National Center For Missing and Exploited Children tells us that one in five children online have been solicited for sex.

Still, I wasn’t prepared for what I was about to see. The next five days would leave my crew and me physically and mentally exhausted.

Even before I arrived on the scene, Mitch and Eric Waggonberg and their team had installed eleven hidden cameras and essentially built a control room on the second floor of the house. The cameras could be panned and zoomed from the second floor. One room over, the volunteers from the vigilante group called Perverted Justice were in regional chat rooms of Yahoo and AOL, posing as 12, 13 or 14 year old kids. They posted profiles with pictures of boys and girls who were unmistakably underage. And huddled in with them, a computer researcher was standing by to dig into the backgrounds of men who came to our house to meet a child for sex.

Video: Some of the men we met
I arrived at our house on a Wednesday morning about 9 a.m. By noon we were expecting our first visitor. He was 54 and called himself “Redbd” on line. He thought he was talking to a 13-year-old boy named Conrad. Redbd acknowledged Conrad’s age saying he was “sooo soo young.” He asked “Conrad” about his sexuality and his sexual experience. Then he sent “Conrad” pictures of himself so explicit we can’t show you. And then he was walking up the driveway to our home. He was confident, comfortable. He even parked right in the driveway. I was standing in the next room, watching on a monitor as he walked into the kitchen. The decoy said: “Hey, spilled Diet Coke on my shirt, I have to go change.” The man offered to help.

As a correspondent in these kinds of situations, you’re always a bit anxious. Redbd didn’t look violent, but you never know how someone in his position is going to react, especially because Redbd was a prominent man who had a lot to lose by being exposed. Redbd was a rabbi at an organization that works with young people. At first he was calm, even though he clearly knew he was in a lot of trouble. Then he became agitated and wanted to know who I was. I suddenly felt a bit on the defensive. When I told him who I was, the camera crew came out of the next room and he started after me. Our security provider intervened and ultimately the rabbi left. Later, in a series of phone calls to us, the rabbi claimed he had done nothing wrong.

All of this happened on the first day of our investigation. He was the first of 19 men who would walk in our house. I knew then, it was going to be a long week.

One after another, a parade of predators showed up at our house. Each confrontation was unique. Sometimes on these undercover investigations you feel almost exhilarated when you catch someone in the act. This time though, it was just plain pathetic and frightening to see first hand how many men would do something like this.

Besides the rabbi, there was a doctor, a special education teacher, an army man, a defense contractor, a medical student… the list goes on. Not one of these men, if you saw him on the street would stand out in a crowd. Some were defiant, claiming they’d done nothing wrong. Many said this was the first time they’d ever done anything like this and they weren’t really going to go through with it. Some broke down and admitted an addiction to the Internet.

NBC

Perhaps the most memorable moment though was when a guy actually walked into our home naked. That’s right: Naked. I knew, based upon his chat with the decoy that this might be a possibility. I never really thought the man would do it. But, on the second evening of our investigation, there he was walking into our kitchen wearing nothing, carrying a 12-pack of beer looking to hook up with a 14-year-old boy. I was standing in the next room looking at the monitor, shaking my head in disbelief. He’s sitting on a stool naked and now I have to go confront him and do an interview with him. That was a TV first for me.

Fortunately, there was a towel nearby that I could give him to cover up.

What does your daddy do for a living? My kids and virtually anyone else I told about my interview with naked-guy thought this was hysterical… that is until I told them what this same guy did the next day. It highlights the danger and the prevalence of men online trying to solicit children. Within 12 hours of the encounter at the kitchen counter, the very same man was in a chat room talking to a decoy posing as a 13-year old boy. There’s sex talk and he sets up a meeting at a fast food restaurant.

But, instead of meeting a 13-year-old, he meets me with a camera crew. Again, I confront the man.

Dateline wires the home of a volunteer, Jenny, from top to bottom with hidden cameras. Then she called repairmen to her house for a simple problem we created as a test with Jenny's pool. NBC's Chris Hansen reports.